Electrically-heated shaft-furnace.



' J. s. BDSTRGM.

ELEGTRICALLY HEATED SHAFT FURNACE. APPLIOATI'QN'IILED MAR. 30, 1906.

PATENTED AUG. 6, 1907.

2 SHEETSSHEET 1 PATENTED AUG. s, 1907. v J. s. EDSTROM. ELEOTRIOALLY HEATED SHAFT FURNACE.

A'P LIO TION ILED MA .30

JOHANNES- SIGFRID EDsTaoM, on VESTERAS, SWEDEN.

Specification of Letters Patent.

'ELECTRICALLY-HEATED SHAFT-FURNACE.

Patented Aug. 6, T:

Application filed March 30, 1906. Serial No. 308,973.

To all whom it mag concern:

Be it known that I, JOHANNES SIGFRID Ensrnoir, a subject of the King of Sweden, and a resident of Vesteras, Sweden, have invented a new and useful linprovem ent in Electrically-Heated Shaftd urnaces, of which the following is a specification, reference being had to the drawings accompanying and forming a part hereof.

This invention relates to improvements in electrically heated shaft-furnaces.

In the usual blast-furnace-processes it is as well known necessary to keep the addition of fuel so large in relation to the ore that the fuel will be sufficient for the reduction of the ore well as for the melting oi the reduced metal. The heat created by the combustion of the fuel is, however, not so high that the reduced iron is obtained in a pure condition but it is necess for the melting that the iron absorb a comparatively large quantity of carbon so that it will be transferred into raw iron and thus having its melting point lowered. It has been proposed for direct production of malleable iron from ore to introduce electric energy into. the lower part of the blast-furnace in order to produce the increase of heat necessary for melting the reduced iron without the iron absorbing so much carbon as to rorm pig iron and in order simultaneously to obtain a retining of the metal by keeping the melted metal. at a high temperature by the influence of the electric energy introduced into the furnace.

The present invention relates to a iurnace construction, in which the introduction of the electric energy will take place in a very satisfactory manner and to such an extent that the temperature necessary for performing the process will be obtained. The invention is based on the introduction of the electric energy by inducing the melted mass by means of an alternating magnetic" field. The whole melted mass of metal is uniformly induced, whereby the melted metal will be uniformly heatedand the obtaining of a uniform and homogenous product will be secured. This is rend cred possible by a special construction of the furnace, the same according to the present invention being carried out in such manner that the hearth of the same forms an annu ar chamber of uniform or substantially uniform cross-section and is arranged as induced member of an electric transformer or generator, the iroitcore oi which passes through the said hearth. By this means it is possible to induce in the he'arthunaterial itself, if the same'be of electrically conducting material, or in the melted mass a secondary current which. heats the melting bath to the llOlllPUl'fittLllU required for the performanc of the process aimed at.

Since the W ole upp r surface of the inciting bath or a considerable part thereof is no covered, it is obvious that the heat radiating therefroni'will r -heat the overlying noi nicltcd parts of the charge and thus accelerate the melting of the reduced metal, before the latter has absorbed any larger quantity of carbon, as well as the reduction of the metal. v

The present device is applicable to blast-furnaces in which the essential part'of the heat is produced by'the combustion of an excess of fuel by means of a blast as off, which in this case consist substantially ofoxid of carbon, may in welllcnown manner be burned in the parts oi the shalt above the zone of reduction by the supply of blastnir for preliminary heating of the charge, or they may be accumulated and utilized for other purposes. 4

For practical reasons it is suitable to make the inner parts of the hearth of an electrically conducting mate rial, so that the same form a crucible or a closed circuit around the melted metal and are likewise induced by the magnetic lines of force flowing through the central part of the hearth, whereby a iurtherincrease of heat may be obtained.

In the accompanying drawings I have illustrated some embodiments of my invention.

Figure 1 shows a vertical section of a blast-furnace constructed in accordance with my present invention. Fig. 2 is a horizontal section on line 11-11 in Fig. 1. Fig. 3 is a vertical section line 1II-III in Fig. 2. Fig. 4 shows a vertical section of a second form of a blast-furnace. Fig. 5 shows a vertical section oi a third form of a blast-furnace having a transformerdevice embodying my invention. Fig. 6 is a hori-= zontal section on line VI-VI in Fig. 5. Fig. 7 is a vertical section at right angles to that shown in Fig. 5.

The section shown in Fig. 5 is taken on line V-V in Fig. '7, and the section shown in Fig. 7 is taken on line Vl.[-Vl.I in Fig. 5.

in the form shown in Figs. 1-3 the shaft 1 is annular along the whole height of the iurnace,acentral core 2 being arranged in the same. At the lower end the said core is hollow, and at some distance above the bottom is arranged a likewise hollow vault 3 between the said core and the wall of the furnace. .Underneafh the said vault and in the bottom of the furnace is provided a channel which "1s "m communication with the lower end of the channel in the said central core. In the U-shaped channel' thus. f ornie d, which. is 'heatdnsulated from the furnace chamber the masonry, is insertedvan iron-core 4 of as'uitable construction, and the said core is provided with aprimary winding 5 which is supplied with alternating current of suitable frequency and may be provided.

on the outer part of the iron-core, as is shown, or on any other or eventually all of thesidesof the core. As willbeeasily understood the hearth of tliefurnace here forms aclosed circuit around the central partof the; core, so th'at the melted metal accumulated in the hearth will constitute the secondary member of a transformer, the other parts of which are constituted by the iron-core 4 and the primary winding 5. The

hearth is provided with an outlet am the metal and an-oritlet? for the slag in the usual manner, the outlet 6 being preferably provided at a distance above the bottom oi the hearth in order that on the said bottom'may aftereach draft always remain a closed conductor crossr'sectionthat is-suitable for taking up the electric energy. If the furnace is to be used while simultaneously supplying a blast it may be provided with t wyers of thensual arrangement. The charge is-intrbduced at the top asis usual in shaftfurnaces and the working is'continuous. When a ,sufiicient quantity of melted metal has been accumulated in the hearth, the metal is drawn and it is obvious that on account of the comparatively long time between the drafts, during which the melted metal is keptzat a" high temperature, the metal is exposed to an effective refining, so that a product of high quality will be obtained from a suitable charge.

' is provided only in the lower part of the shaft.

mediate wall 8 at the widest part of the shaft may be dispensed with, if desired.

As will be easily understood, the invention is applicable to any shaft-construction, provided the lower part of the latter forms an annular chamber which enables the melted metal accumulated therein, or the hearth-.

material itself, to be induced by means of one or more magnetic circuits passing through the hearth.

In order to prevent the iron-core from being ex cessively heated the core may in all forms of my invention be cooled by means of air, water or any other suitable fluid circulating in or around the core. When a central core of masonry extending along the whole height of the shaft is used, the'said core 'may, prefer ably, be made hollow, as is shown as an example in' Fig. l, in order to obtain a ,ventilation channel from the chamber inclosing the iron-core, the-said channel working as a chimney and being capable of drawing in a quantity of cold air suflicient for cooling the ironcore, whereby mechanical arrangements for the same purposeeventually will be dispensable.

Obviously the use of the furnaces embod g my presentinvention is not limited to the reduction of iron-ore. For instance, they may advantageously be used ior'continually melting and refining oi pig-iron, to which is added langrage, more, or of other mixtures for'producing malleable iron or steel of high quality. They may further be used for the reduction oioxids of metal of all kinds, where the metal in the reduction is obtained in liquid condition, also alufminium, the excess of heat obtained electrically ren deriiig it possible to obtain any desired temperature.

necessary for the performance of metallurgic processes.

The invention may also be used in zinc-shait-furnaces, if, for instance an arbitrary'closed conductor,

which is not injured or volatilized at the temperatures' hearth forming an annular horizontal chamber of uniform or substantially uniform cross-section for taking up the melted material and placed directly beneath the shaft, and an iron-core for inducing eLectric currents in thesard' melted material, substantially as and for the purpose set forth,

2. In an electric furnace the combination, of a shaft, a hearth forming an annular horizontal chamber of substantially uniform cross-section and placed directly beneath the shaft, a hollow core of fire-proof material in the said hearth, an ir0ncore in the firstrnentioned core, and a primary winding on the said iron-core, substantially as and for the purpose set forth.

3. In an electric furnace the combination, of a shaft, a. hearth forming an annular horizontal chamber'of substantially uniform cross-section 'and placed directly beneath the shaft,-a central hollow core of fire-proof material in the said hearth, a hollow extension on the said core. extending upwardly through the shaft, an iron-core in the first-mentioned core, and a primary winding on the said iron-core, substantially as and for the purpose set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

I JOHANNES SIGFRID EDSTRilMJ Witnesses ll-I. FETTERSTROM, 1. G. IIOLM. 

